Eastern Tiger Swallowtail (Papilio glaucus) (Linnaeus, 1758)

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Diagnosis: This species was probably the first butterfly in North America to be described by Europeans. It was figured by John White, one of the early colonists in Virginia. Its common name is very appropriate, with the bold black tiger stripes over the yellow ground colour. It has a narrow blackband along the inner hindwing margin. The black female form with slightly darker stripes is rarely encountered in southern Ontario, most often at Point Pelee. Wingspan: 75 to 100 mm.

Subspecies: Only the nominate subspecies is found in Canada now that Canadian Tiger Swallowtail (P. canadensis) is treated as a separate species.

Range: The Eastern Tiger Swallowtail is widespread throughout the eastern U.S. It reaches into Canada only in southern Ontario north to the Bruce Peninsula, the Rideau Lakes and Grenville County in eastern Ontario. Reports of this species from Nova Scotia are based on several accidentally mislabelled specimens in the Canadian National Collection in Ottawa. These specimens emerged in Truro from pupae brought from Illinois.

Similar Species: The only similar species in the Canadian range of this butterfly is the closely related Canadian Tiger Swallowtail (P. canadensis). Papilio glaucus can be separated by the narrow width of the black band on the inner margin of the hindwing, by the marginal row of yellow spots on the underside of the forewing, and by its generally larger size. In canadensis, the marginal row of spots forms a continuous band. [compare images]

Eastern Tiger Swallowtail (Papilio glaucus glaucus), larva. J. Cossey

Early Stages: These are similar to those of canadensis. Papilio glaucus larvae feed primarily on Tulip Tree (Liriodendron tulipifera) and other more southern tree species, such as the Hop Tree (Ptelea trifoliata), found in southern Ontario, but they can eat some of the same foodplants as canadensis, such as cherry (Prunus spp.) and ash (Fraxinus spp.).

Abundance:Papilio glaucus is an uncommon species in most of its Ontario range, except in the southwest.

Flight Season: This butterfly is double-brooded in the northern part of its range. The first generation starts flying in May in Ontario and adults from the second generation can be seen regularly until the end of August. A single specimen was recorded in mid-October at Point Pelee (Wormington, 1983).

Habits: This is a woodland species, but it can regularly be found in fields and along roadsides. Like the Canadian Tiger Swallowtail it is a mud-puddler.

Remarks: There is likely a thin line of hybridization in Ontario between the Eastern and CanadianTiger Swallowtails, where the ranges of the two species are in contact. This situation exists in Michigan. Specimens in the Canadian National Collection from Perth Road in eastern Ontario taken in the spring look like canadensis, but individuals in late July look like glaucus. Papilio glaucus in Ontario may have a spring form that resembles canadensis (see discussion in Hagen et al., 1991).